Opacified pearlescent multilayer louver for verticle blinds

ABSTRACT

Opacified Pearlescent Compounds for Making an elongate louver or assembly of louvers having an improved multi-layer louver configuration comprising an opacified pearlescent outer layer having a claimed range of opacity which substantially or completely occludes an base layer, the increased opacity substantially reduces or eliminates perceptible non-uniformity in coloration, shade change and thickness of the outer layer, while improving resistance to yellowing, processing characteristics, and raw material cost economics.

This is a Continuation of Ser. No. 07/858,385 filed Mar. 25, 1992 nowU.S. Pat. No. 5,194,209.

BACKGROUND OF THE INVENTION

The present invention is directed to novel louvered assemblies forwindow coverings, and more particularly relates to multilayer verticlelouver assemblies having an improved opacified pearlescent outer layer.

Over the last few decades, vertical louvered systems have becomepopular. Typical vertical louvered assemblies comprise relatively thin,elongated vertical hanging slats which are suspended and dependvertically from a mechanism which aligns and orients the slats.Typically the depending slats overlap slightly and can be rotated inunison to infinitely adjust the light or view through the opening. Theslats are made from a wide variety of materials including extruded vinylstrips and are optionally decorated by attaching webs, narrow woven orslit fabrics, or laminated films.

Related to the present invention are vertical slat assemblies involvingcombinations of a slat member and a decorative member which is insertedthereupon to the face, back or both sides of the slat with attachmentmeans. The vertical louver described in U.S. Pat. No. 4,049,038 ('038)comprises lateral inwardly facing attachment means which are flanges onone or both faces of the slat which will receive an insert such as astrip of wallpaper or fabric. U.S. Pat. No. 4,628,980 ('980) discloses alouver of identical shape to '038 but incorporates co-extrudedtransparent flanges. The patentable difference between '038 and '980 isthe transparency of the lateral flanges which are less obtrusive. Incommercial practice, such louvers are made by the co-extrusion of aclear thermoplastic compound for the lateral flanges with an opaquecompound for the rest of the slat.

A Material of choice for co-extruded louver slats of this type ispolyvinyl chloride due to the favorable cost/performance properties ofthis commodity thermoplastic resin.

U.S. Pat. No. 4,195,680 discloses decorative attachments to an '038flanged louver comprising one or more multiple clear or translucenttinted film inserts which allow convenient color changes. Variations incolor are achieved by attaching one or more inserts each of which havedifferent colors and together form a new color.

A pertinent reference relative to the present invention, U.S. Pat. No.4,877,077 ('077) discloses a verticle louver made from co-extruded vinylthermoplastic wherein a transparent outer layer containing a pearlescentpigment is co-extruded with an opaque base layer. The opaque base layeris visible and reflects light through the pearlescent surface layer.Optionally a transparent or translucent tinting color dye isincorporated in the outer layer.

The approach disclosed in '077 has several shortcomings. First, due tothe restriction of transparency, the resulting perceived color of thepearlescent surface is a combination of the colors making up thetransparent layer and the color of the opaque base layer. The appearanceof the louvers are sensitive to minute variations in the coatingthickness which can create the appearance of undesirable streaking forinstance. Imperfections in the consistency of the extruded compound suchas polymer gells are more likely to occur in compounds having low filleror pigment levels in the pearlescent layer yet the '077 patent teachesthe requirement of using a clear transparent compound in order toprovide the basis for obtaining a pearlescent effect.

Secondly, transparent thermoplastic materials including vinyl basedpolymers are susceptible to degradation and yellowing when exposed toultraviolet radiation from the sun or fluorescent lights if notadequately protected. This is particularly problematic where sections ofthe louver ensemble receive varying levels of exposure. Non-uniformityin the thickness of a transparent outer layer can lead to perceptiblestreaking after yellowing occurs even where the entire surface has beenuniformly exposed.

Accordingly, it would be desirable to devise a pearlescent multilayeredlouver not having the aforementioned drawbacks.

SUMMARY OF THE INVENTION

It is an aspect of the present invention to provide an improvedmulti-layer louver having an opacified outer layer within a narrow rangeof opacity which retains a pearlescent effect.

It is a further aspect of the present invention to provide a pearlescentouter layer which is opacified wherein the outer layer substantially orcompletely occludes a base layer.

It is a further aspect of the present invention to provide a pearlescentouter layer having a degree of opacification within the claimed rangewhich substantially reduces or eliminates surface imperfections,yellowing, and the perceptibility of the effects of non-uniformity afterlong term exposure.

It is a further aspect of the present invention to provide an improvedpearlescent compound having higher consistency of quality, reducedmaterial cost and improved melt processing properties for use themulti-layer louver by incorporating opacifying pigment in the outerlayer optionally in combination with particulate fillers.

The present invention specifically encompasses the discovery of a narrowrange of opacity for a pearlescent outer layer of a multi-layer louverwherein a pearlescent luster is retained yet irregularities in thecoloration, noticeable variation in the thickness of the outer layer,and other imperfections are substantially or completely eliminated or atleast increasingly hidden from view as opposed to when a prior art outerlayer is based on a pearlescent clear transparent compound. In additionto improved consistency of appearance, the present invention enablesimprovement in the processing characteristics of the extrudate,improvements in raw material costs and improved inherent long term agingproperties by the incorporation of protective UV/visible light absorbingpigments in the pearlescent outer layer of a multi-layer louver.

It is desirable and advantageous to substantially or completelyeliminate visually perceptible imperfections such as polymer gels orstreaking caused by incomplete dispersion and thickness variationrespectively in the extrudate as frequently occurs in commercialpractice. It was expected that opacification of the outer layer woulddestroy the pearlescent luster, however, a narrow range in the lighttransmittance through the outer layer was discovered which allows anacceptable retention of pearlescent luster thereby providing theaforesaid improvements.

Other objects and advantages of the present invention will becomeapparent from the following detailed description taken in conjunctionwith the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an elevation view of a vertical louver assembly system;

FIG. 2 is an enlarged sectional view taken approximately on line 1B;

FIG. 3 is a further enlarged sectional view of one end of the multilayerlouver slat of FIG. 2 as seen within viewing circle A of FIG. 2 whereina two layer embodiment of a louver is illustrated.

FIG. 4 is an enlarged section view of the same section of a louver ofFIG. 2 as seen within viewing circle A of FIG. 2 wherein a three-layerembodiment of a louver is illustrated.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

A louver system 10 illustrated in FIG. 1 comprises a plurality oflouvers 11 held vertically by a louver track system 12. Louvers 11depend from the track system and are movably aligned. Generally louvertrack systems allow for rotation of the aligned louvers in unison foradjustment of the light or view through the opening and allow forgathering together at one end similar to the gathering of clothdraperies.

As indicated above, the invention involves a combination of integralcombined layers in a louver slat for producing a pearlescent effect. Theenlarged section view of the multilayer slat of FIG. 2 within viewingcircle A is illustrated in FIG. 3 wherein there is seen the lateralsection of louver 11. In reference to louver 11 in FIG. 3, there isshown a base layer 13 having lateral edge 14. Lateral edge 14 on eachside of the base layer 13 generally will have a rounded or an ellipticalcross section. This eliminates sharp edges and can alternatively providea structural stiffening effect if made prominent. The multilayer slat ofFIG. 3 has an opacified, pearlescent upper layer 15.

Opacified upper layer 15 within the claimed range of opacitysubstantially occludes base layer 13 depending on the level of opacity.This is in contrast to the prior art clear transparent pearlescent outerlayer which allows higher light transmission through the outer layerwhich reflects from the base layer at the interface between the layers.Therefore, when employing an opacified outer layer, any colorationpresent in the base layer contributes less perceptible color sincetransmission and reflection at the interface are reduced.

FIG. 4 depicts a multilayer louver having two outer layers 17 and 18surrounding an opaque inner layer 19. One or both outer layers 17 and 18may comprise an opacified pearlescent compound comprising pearlescentpigment in combination with opacifying pigment and optionally filler orcolor pigments.

Preferably the base layer 13 or 19 is of a light shade. The opacifiedupper layer has pearlescent pigmentation, opacifying pigment andalternatively can be colored with the addition of light pastel dispersedpigments for example. The opacified upper layer has a pearlescentpigment in amounts effective to give the desired level of pearlescentappearance. The opacifying pigment is present in the opacified upperlayer in effective amounts to give the desired opacity for a giventhickness of the upper layer.

Transparent tinting dyes are not as effective in providing coloration inan opacified layer therefore these are not preferred in providing addedcoloration to the opacified outer layer of the louver. Opaque colorpigments are more efficient in providing added coloration to thepearlescent layer therefore these are preferred when desired.

Louver slats generally are one to five inches wide, and typically 3.5inches wide. The slats typically have a total thickness of from about0.030 to about 0.035 inch in the medial portion. The multilayer slats ofthe present invention contain at least one outer layer which cancontribute from about 0.003 to about 0.009 inch, preferably about0.004-0.005 inch of the total web thickness. The rounded lateral edgesform a circular or ellipsoid solid cylinder which is an integral portionof the base layer, and typically has a radius of curvature of about0.025 inch. As seen in the example embodiment of FIG. 2, the thinpearlescent layer covers one surface of the base layer. A multilayerslat such as a two layer slat can alternatively be constructed as aninsert to be placed on the face of an existing flanged louver such as an'038 type louver. In this instance, the insert is preferably thinnerthan the louver which it is inserted thereon, therefore the base layerwill have a thickness of about 0.004 inch and the clear transparentpearlescent layer will have a thickness of about 0.007 totalling about0.011 inch typically for an insert.

Pearlescent pigmentation referred to here means pigment having the sheenor luster of a pearl such as the oyster pearl. Pearl essences are wellunderstood in the thermoplastic compounding art and a detaileddescription of the processes of isolating and purifying natural orsynthetic pearl essences is beyond the scope of this disclosure. Anexample of a commercially available pearlescent pigment suitable for usein the outer layer of the louver herein described is available from TheMearl Corporation under the "Superwhite" Trademark.

The layers comprising the louver can be made from a variety ofmaterials. For instance the base layer can consist of an aluminum stripand the outer layer can be a pearlescent paint based on a suitablebinding matrix such as alkyd resin or urethane enamel. In this instancethe outer layer is coated or applied to the base layer which is asubstrate for the outer layer.

The resin of the outer layer in which the pearlescent pigment system andopacifying pigments are dispersed is referred to as a matrix. When theouter layer is made from a thermoplastic compound, the matrix is thethermoplastic resin in which the pigments are dispersed. A predominantthermoplastic matrix in commercial use is polyvinyl chloride. Polyvinylchloride compounds are widely used in commercially available singlelayer extruded louvers. The preferred form of the multilayer louvertherefore consists of coextruded thermoplastic compounds based on poly"vinyl" chloride. Typical opaque rigid vinyl compounds which aresuitable for the base layer are GEON® 87408 and GEON® 87600 commerciallyavailable from B. F. Goodrich Company, Geon Vinyl Division, Cleveland,Ohio. These compounds consist essentially of 100 parts polyvinylchloride polymer, about 1 part of thermal stabilizer, about 3 parts ofprocessing aid, about 5 parts of lubricant, about 10 to 20 parts ofcalcium carbonate, about 5 to 15 parts of titanium dioxide and aneffective amount of coloring pigment to provide the desired shade.Optionally, this compound can include an effective amount of impactmodifier.

It has been previously disclosed a conventional pearlescent polyvinylchloride compound based on a clear transparent vinyl compound suitablefor a coextruded outer layer of a vinyl based louver. This compound isdesignated as GEON® 87513-028. Other than the pearlescent pigmentation,no opacifying pigment is present in this compound and U.S. Pat. No.4,877,077 teaches the requirement that none be present. The novelpearlescent compounds of the present invention require the presence ofadded opacifying pigment in addition to pearlescent pigment in order toachieve the advantages hereinabove established. The novel opacifiedpearlescent compounds of the present invention preferably contain 100parts of polyvinyl chloride polymer, 2 to 3 parts of one or more heatand light stabilizers, 8 to 10 parts of impact modifier, 1 to 2 partsprocessing aid, 2 to 10 parts plasticizer 0.1 to 3 parts of titaniumdioxide, an effective amount of pearlescent pigment and 0.5 to 1.5 partsof one or more lubricants.

One apparatus for producing co-extruded multilayer slats of the presentinvention is a conventional thermoplastic extrusion device incorporatingslotted coextrusion dies for instance having internal passages whichprovide for combining of the layers before the extrudates reach the dietips under typical laminar melt flow. A slotted die can be fabricated byanyone skilled in that art and utilized in a conventional manner onconventional extrusion equipment to co-extrude the multilayer slats.Therefore a detailed discussion of this componentry is beyond the scopeof the present disclosure. Those skilled in the art will recognize thatthe multilayer slats of this invention may be fabricated by acalendering process. In this process generally a fluxed compound is fedto a calender stack. The fluxing of the compound can be carried out in acontinuous mixer. Typically a mixer such as a planetary gear extruderprovides controlled delivery of heat and work input to the compound inorder to achieve uniform feed rate, color, gage and surface quality inthe calendering step. A brief outline of this process is provided inModern Plastics Encyclopedia, McGraw-Hill Inc., New York (1988).

It is also anticipated that the method of fabrication of the louver ofthe present invention can include the extrusion of an opacifiedpearlescent outer layer over a metal base layer such as an aluminumstrip. The aluminum can optionally be coated to provide white or anydesired color. It is possible with the degree of opacification providedin the outer layer of the multilayer louver of the present invention toutilize a wide variety of materials comprising the base layer since thebase layer is substantially occluded and receives substantially lessincident light through the opacified outer layer. All of the anticipatedvariations of fabricating a multilayer louver having an opacified outerlayer within the claimed range of opacity can be reduced to practicewith a reasonable trial and error effort and such variations andapproaches are understood as within the scope of this invention.

In the examples below, the control and experimental thermoplastic vinylcompounds were milled into films of 0.004 inch thickness. Thereflectance ratio method of opacity determination was measured using aPhotovolt Model 575 reflection and gloss meter following the proceduresaccording to TAPPI useful method T 425 om-86. Examples 2-8 represent theseries of opacified pearlescent outer layer compounds with varyingamounts of added titanium dioxide listed below in weight percent basedon the weight of the control. Visual inspection was made to determinethe presence of pearlescent luster. The reported reflectance ratio wasexpressed as:

    opacity=black reflectance/white reflectance X 100

EXAMPLES

    ______________________________________                                                TiO.sub.2                                                                              %            Opacity                                         Example Level    Reflectance White                                                                          (B/W ×                                                                        Pearlescent                               No.     Wt. %    Black        100)  Appearance                                ______________________________________                                        CONTROL 0.0      68.1    35.3   51.8  GOOD                                    2       0.1      70.8    42.9   60.6  GOOD                                    3       0.2      72.5    46.5   64.1  GOOD                                    4       0.3      73.9    48.4   65.5  GOOD                                    5       0.5      75.0    53.2   70.9  GOOD                                    6       1.0      77.1    60.6   78.6  GOOD                                    7       2.0      79.9    70.2   87.9  GOOD                                    8       5.0      83.8    80.5   96.1  POOR                                    ______________________________________                                    

As can be seen from the table above, Examples 2-8 exhibit higher percentreflectance ratios compared to the control which is the prior art cleartransparent pearlescent compound. The addition of titanium dioxideopacifying pigment in Examples 2-7 maintain an adequate pearlescentluster and also yield improvements in appearance and uniformity. At apercent reflectance ratio higher than about 90%, the pearlescent effectis no longer perceptible. A titanium dioxide level of 5% in Example 8exhibited a 96.1% reflectance and the pearlescent luster was absent.

From the foregoing results, it appears that the presence of aperceptible pearl luster requires a minimum threshold level of lighttransmission through the outer layer which corresponds to an opacity ofabout 90% and below according the test method employed. This minimumlight transmission provides sufficient intensity of light refractionover the distances between pearlescent particles within the outer layerproducing the pearlescent effect. Such a relationship has not heretoforebeen disclosed pertaining to a multilayer louver. Moreover it has notheretofore been disclosed that pearlescent effects can be observed withthe use of added opacity enhancing ingredients at the effective levelsobserved.

It is anticipated that any combination of opacifying enhancers can beused including opaque coloring pigments. Optionally, inert fillers nothaving efficient opacity enhancement can be included in combination withpreferable opacifying pigment such as titanium dioxide.

In an alternative embodiment of the multilayer louver, the base layer isnot pearlescent and not entirely opaque but can exhibit a reflectanceratio according to TAPPI method T 425 om-86 of between 0% and 99%.Alone, this base layer would appear translucent at lower reflectanceratios, however, it can contribute desired extent of light blockingproperties in proportion to the opacifying pigmentation incorporated.Since the outer layer can exhibit up to about a 90% reflectance ratio at4 mils, the outer layer will almost completely occlude the base layerand can contribute substantial blocking of light.

Due to the improved processing characteristics such as uniformity ofdispersion, melt strength and smoothness of extrusion, it is preferredto include fillers such as calcium carbonate for example. As mentionedabove, other advantages stem from the added opacifier(s) and filler(s)such as uniformity of color dispersion and reduction in the incidence ofpolymer gells.

Various changes and modifications may be made in carrying out thepresent invention without departing from the spirit and scope thereof.Insofar as these changes are within the purview of the appended claims,they are to be considered as part of the invention.

It is claimed:
 1. An opacified pearlescent composition comprising:(a) at least one thermoplastic polymer matrix, (b) an effective amount of at least one pearlescent pigment for providing pearlescent luster, and (c) from 0.1 to 3 parts of titanium dioxide opacifying pigment per 100 parts by weight of said thermoplastic polymer, wherein a 4 mil thickness of said composition has a percent reflectance ratio according to TAPPT method T 425 OM-86 of from about 60% to about 90%.
 2. A composition of claim 1 wherein said thermoplastic polymer is a polyvinyl chloride polymer. 